Stuck at 19/20 Supreme Loot

Hello All, I finished the campaign and I kept playing the missions. There is a counter at the top-right side of the screen with " Supreme Loot: 19/20 " . It does not increases regardless how may Supreme equipment I get.

Did anybody reach 20/20? Any idea of what might be going on?

Thanks.

the count I think is of the unique supreme loot, not the quantity, got my 20/20 count after about 9 veteran missions (basically after 27 veteran side missions).